22 patients with chronic pancreatitis took 8 mg of delta-9-tetrahydrocannbinol (Δ9-THC) with placebo diazepam or placebo Δ9-THC with diazepam at 2 sessions in a randomly allocated sequence for this crossover trial. Blood samples were examined for the pharmacokinetic and pharmacodynamic properties of Δ9-THC, and reduction in pain was measured by the VAS scale. Bond and Lader visual analogue scales were used to assess mood and behavioral changes and the Bowdle questionnaire was used to assess the psychedelic effects of Δ9-THC. Results indicate that Δ9-THC 8 mg was not significantly effective for pain reduction compared to diazepam but was well-tolerated with mild and moderate adverse effects. There was no significant score difference between Δ9-THC and diazepam for the Bond and Lader questionnaire or balance measurements, but anxiousness was significantly increased after Δ9-THC compared with diazepam according to the Bowdle questionnaire.